Hi Martin, concerning the tag spectral-norm, it seems that it is a strict subcategory of matrix-norm, which has only 19 questions tagged with. It seems un-necessary to have this tag. Would making a Synonyms a good choice?

The tag matrix-norms is relatively young - June 2018. Maybe there just wasn't enough time to populate it.

I would guess that non-negligible part of posts tagged matrices+norm would be tagged with this tag, had it existed at the time.

Personally, I'd say matrix-norms is worth keeping. The tag spectral-norm might be too specific, but it would be better to hear from users who regularly post in this topic.

@JohnMa Perhaps it could be reasonable to ask in the tag-management thread to find out what other users think about this.

Or, if you prefer, you can wait a bit first - to see whether somebody else comments on the issue here in chat.

@MartinSleziak as you may have notices, I created locked-posts and merged with syn tha "locked-questions" into it

In fact, I did not notice. In any case, it seems like a good idea.